Aquatic tow rope with shock absorber



June 18, 1963 N. K. FLORENCE AQUATIC TOW ROPE WITH SHOCK ABSORBER FiledDec. 5, 1960 All h 6 G mm mm f WH J. 1K. f w w N R Y B United StatesPatent Patented June 18, 1963 mce 3,094,096 AQUATIC TOW ROPE WITH SHOCKABSORBER Nilo K. Florence, Tulsa, Okla. (1449 SW. 65th St., OklahomaCity, Okla.) Filed Dec. 5, 1960, Ser. No. 73,606 2 Claims. (Cl.114--235) The present invention relates to aquatic tow ropes, moreparticularlygg p qugt i c tow ropes ayir g s hp c a Qe siged to reducemarrow-strain" on thearmslof a makierm In the sport of water skiing, itis customary for the skier to squat in the water holding his end of thetow rope, while the boat behind which he is to be towed takes up theslack in the line. When the line first becomes taut, the skier islargely immersed in the water and his inertia and the resistance of thewater to his movement are quite great. The boat, however, is usuallytraveling at a relatively high speed. The result is that a great strainis imposed very suddenly on the arms of the skier.

Accordingly, it is an object of the present invention .to provide anaquatic tow rope with a shock absorber dewmawwit Another object of thepresent invention is the provision of an aqua-tic tow rope having ashock absorber that will not sink.

Finally, it is an object of the present invention to provide an aquatictow rope with shock absorber, that will be relatively simple andinexpensive to manufacture, and rugged and durable in use.

Other objects and advantages of the present invention will becomeapparent from a consideration of the following description, taken inconnection with the accompanying drawings, in which:

FIGURE 1 is a view in section of a shock absorber for an aquatic towrope according to the present invention, showing the shock absorberfully relaxed and the float in place;

FIGURE 2 is a view of the structure of FIGURE 1, with the float removed,showing the normal position of the parts while the skier is traveling atthe same speed as the boat;

FIGURE 3 is a view similar to FIGURE 2 but showing the parts in theposition they initially assume when the tension in the line is thegreatest;

FIGURE 4 is an exploded assembly view of the shock absorber and float ofthe present invention; and

FIGURE 5 is a view showing an aquatic tow rope according to the presentinvention with included shock absorber.

Referring now to the drawing in greater detail, there is shown anaquatic tow ro e indicated e oral].

indicated generally at 5 and extend lengthwise in the same direction asshock absorber 5.

Shock absorber 5 is comprised of an elongated piston rod 7 having an eye9 at the end to which the adjacent section of filament 3 is tied, and apiston 11 at the other end. Piston 11 moves in closely slidingrelationship within a cylinder 13 having an integral rod 15 extendingaxially therefrom in the opposite direction from piston rod 7. Rod 15terminates at its free end in an eye 17 in which the adjacent section offilament 3 is tied. Cylinder 13 is comprised of a base portion 19 towhich rod 15 is attached, circular end edges and a detachable endportion 21 in screw-threaded engagement with base portion 19. Endportion 21 has an axial opening through its end remote from rod 15, andpiston rod 7 slides in closely fitting rel-aatl d;

"in a aifbiibii "Th ad acent ends of the sections of 55 filament *3 are-tied to opposite ends of a shock absorber 2 tionship through thislatter opening. Base portion 19 and end portion 21 are also providedwith vent openings 23 in their end walls so as to avoid any air or watercushion eflfect upon movement of piston 11 in cylinder 13.

Disposed in cylinder 13 between piston 11 and the end of end portion 21remote from rod 15 is a pair of coil compression springs 25 and 27. Whenrelaxed, spring 25 is of a length at least as great as cylinder 13; butspring 27 when relaxed is of a length only about two thirds as great ascylinder 13, as will be seen in FIGURE 1. However, although spring 25 isrelatively long, it is relatively weak; and spring 27, while relativelyshort, is relatively strong. Spring 25 is disposed outside of andconcentric with spring 27 and both springs are coaxial with piston rod7, piston 11, cylinder 13, rod 15, base portion 19 and detachable endportion 21.

Piston 11 is provided with an annular groove 29 that provides a shoulderfor the outer spring 25, while the closed end of end portion 21 isprovided with a similar groove 3-1 confronting groove 29 to provide ashoulder :for the opposite end of spring 25. Piston 11 is provided witha smaller annular groove 33 at the juncture of piston 11 and piston rod7, to provide a shoulder for the inner spring 27; while the closed endof end portion 21 is provided with a corresponding confronting groove 35to provide a shoulder for the other end of spring 27. The springs arethus retained in place on and act between the closed end of end portion21 of cylinder 13, and the confronting or under the side of piston 11.

In order to keep the shock absorber afloat so that it does not drag downthe tow rope with it and so that it drains off any water that enters it,a float 37 is provided, which encompasses shock absorber 5. Float 37 isin the form of two complementary opposed sections 39 each of which ishalf of the float. Sections 39 are elongated and hollow but water tightand waterproof and may for example be of metal or strong plastic. Ontheir interior, each is provided with half of each of a pair of opposedgrooves 41 in which the end marginal edges of cylinder 13 are snuglyreceived when the float halves are assembled about the shock absorber.At each end, the float has an opening 43 extending axially therethroughin communication with the interior of the float between grooves 41. Halfof each opening 43 is provided in each of sections 39 of float 37, sothat when the sections are brought together in the assembledrelationship shown in FIGURE 1, each opening 43 will be completed byeach section 39. Each section 39 of float 37 is also provided with apair of axially spaced apart semi-circular external grooves 45, which inthe assembled relationship of the float form a pair of axially spacedapart annular grooves in each of which is disposed a spring clip 47 forresiliently retaining the float sections 39 in assembled rela- [tionshipabout the shock absorber with rods 7 and 15 extending through openings43 but with eyes 9 and 17 disposed outside of float 37 even in the fullyrelaxed position of the shock absorber. In the assembled relationship,the axis of the float is coincident with the axis of the shock absorber.

It will also be appreciated that the float, in addition to keeping theshock absorber from sinking, assures that the shock absorber will belargely out of the water so that Water that gets inside the shockabsorber will tend to drain out. This, in turn, assures that air ratherthan water will ordinarily surround the piston moving within the shockabsorber, thereby to give the shock absorber a much more sensitive andrapid response to shocks in the tow rope than if the shock absorber wereusually immersed and filled with water during use.

The operation of the device will now be apparent. Before the line istensioned, the shock absorber has the position shown in FIGURE 1. Uponthe application of tension, however, the piston moves in the cylinderuntil the position of the parts is reached as shown in FIGURE 2. Duringthis initial portion of the movement of the piston in the cylinder, onlyrelatively weak spring 25 is compressed. However, when the parts reachthe position of FIGURE 2, then not only weak spring 25 but also strongspring 27 undergoes compression. The force necessary to move the partsbetween the positions of FIGURES 1 and 2 is relatively small compared tothe force needed to move the parts between the positions of FIGURES 2and 3. Thus, there is initially a weak and then a strong shock absorbingaction in the line. The combined strength of springs 25 and 27, however,is sufficient to relieve the sudden strain on the arms of the waterskier, and the towing boat and the skier are soon moving at the samerate of speed.

After the initial tension in the tow rope is relieved by the skiercoming up to speed, the tension in the rope quickly falls off to thatneeded merely to move the skier at the same rate of speed as the boat.Strong spring 27 can expand until it is relaxed, whereupon the partsagain assume the position shown in FIGURE 2, in which spring 25 islargely absorbing the small shocks encountered when water skiing at thesame speed as the boat.

Thus, the weak spring in combination with the strong spring in theenvironment of an aquatic tow rope assures that the sudden shock will beapplied to the arms of the skier only gradually, in two stages, and thatwhen the skier is then up to speed, the small shocks thereafterencountered will be counteracted much more sensitively by only the weakspring. The float encasing the shock absorber, in turn, assures not onlythat the tow rope will not sink, but also that the shock absorber willbe ordinarily above the water and will remain largely drained of waterthat otherwise would interfere with the sensitivity of its response tosudden shocks.

In view of the foregoing, it will be obvious that all of the initiallyrecited objects of the present invention have been achieved.

Although the present invention has been described and illustrated inconnection with a preferred embodiment, it is to be understood thatmodifications and variations may be resorted to without departing fromthe spirit of the invention, as those skilled in this art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the present invention as defined by theappended claims.

What is claimed is:

1. An aguatic tow ropecomprisin? ailexible lament.

in twg seotions, one section being secured to one end of a piston rodhaving a piston at the other end and the other section beinginterconnected with a cylinder in which the piston slides, coilcompression spring means surrounding the piston rod within the cylinderand acting between the cylinder and the piston continuously yieldably tourge the piston rod into the cylinder, the cylinder having a rodextending a substantial distance axially therefrom in alignment with butin the opposite direction from the piston rod, said other section offlexible filament being secured to said cylinder rod, said piston rod inits farthest position within the cylinder extending a sub stantialdistance outside the cylinder, and a float encasing and mounted on thecylinder, the float extending a substantial distance beyond each end ofthe cylinder and having a rounded exterior end at each end thereof, thefloat closely encompassing both said rods for a substantial distancebeyond each end of the cylinder but being spaced from at least thepiston rod thereby to permit free movement of the piston rod within thefloat, said sections of the flexible filament being secured to said rodsendwise beyond the float, the float being in two separable sections,

each section defining a portion of each of a pair of passageways throughwhich said rods extend, the cylinder having a cylindrical externalcontour including a circular end edge at each end of the cylinder, thefloat sections each having a pair of semicircular recesses thereinspaced apart the length of the cylinder so that the float sections aresupported on the cylinder by contact of the cylinder end edges in thesemicircular float section recesses, the float sections being spacedoutwardly of the cylinder between the semicircular recesses.

2. An aquatic tow rope as claimed in claim 1, said cylinder having apair of opposite end walls and openings through both end walls thereofto permit the free flow of fluid into and out of the ends of thecylinder upon movement of the piston within the cylinder, the floatbeing spaced from both said rods and from said openings so as to providepassages for the flow of fluid about both said rods and through each endof the float.

References Cited in the file of this patent UNITED STATES PATENTS593,788 Stone Nov. 16, 1897 904,473 Davis Nov. 17, 1908 1,444,876 HansonFeb. 13, 1923 2,153,489 Whitis Apr. 4, 1939 2,241,851 Gilstrap May 13,1941 2,395,892 Lontz Mar. 5, 1946 2,731,758 Coe Jan. 24, 1956 2,843,967Kruse July 22, 1958

1. AN AQUATIC TOW ROPE COMPRISING A FLEXIBLE FILAMENT IN TWO SECTIONS,ONE SECTION BEING SECURED TO ONE END OF A PISTON ROD HAVING A PISTON ATTHE OTHER END AND THE OTHER SECTION BEING INTERCONNECTED WITH A CYLINDERIN WHICH THE PISTON SLIDES, COIL COMPRESSION SPRING MEANS SURROUNDINGTHE PISTON ROD WITHIN THE CYLINDER AND ACTING BETWEEN THE CYLINDER ANDTHE PISTON CONTINUOUSLY YIELDABLY TO URGE THE PISTON ROD INTO THECYLINDER, THE CYLINDER HAVING A ROD EXTENDING A SUBSTANTIAL DISTANCEAXIALLY THEREFROM IN ALIGNMENT WITH BUT IN THE OPPOSITE DIRECTION FROMTHE PISTON ROD, SAID OTHER SECTION OF FLEXIBLE FILAMENT BEING SECURED TOSAID CYLINDER ROD, SAID PISTON ROD IN ITS FARTHEST POSITION WITHIN THECYLINDER EXTENDING A SUBSTANTIAL DISTANCE OUTSIDE THE CYLINDER, AND AFLOAT ENCASING AND MOUNTED ON THE CYLINDER, THE FLOAT EXTENDING ASUBSTANTIAL DISTANCE BEYOND EACH END OF THE CYLINDER AND HAVING AROUNDED EXTERIOR END AT EACH END THEREOF, THE FLOAT CLOSELY ENCOMPASSINGBOTH SAID RODS FOR A SUBSTANTIAL DISTANCE BEYOND EACH END OF THECYLINDER BUT BEING SPACE FROM AT LEAST THE PISTON ROD THEREBY TO PERMITFREE MOVEMENT OF THE PISTON ROD WITHIN THE FLOAT, SAID SECTIONS OF THEFLEXIBLE FILAMENT BEING SECURED TO SAID RODS ENDWISE BEYOND THE FLOAT,THE FLOAT BEING IN TWO SEPARABLE SECTIONS, EACH SECTION DEFINING APORTION OF EACH OF A PAIR OF PASSAGEWAYS THROUGH WHICH SAID RODS EXTEND,THE CYLINDER HAVING A CYLINDRICAL EXTERNAL CONTOUR INCLUDING A CIRCULAREND EDGE AT EACH END OF THE CYLINDER, THE FLOAT SECTIONS EACH HAVING APAIR OF SEMICIRCULAR RECESSES THEREIN SPACED APART THE LENGTH OF THECYLINDER SO THAT THE FLOAT SECTIONS ARE SUPPORTED ON THE CYLINDER BYCONTACT OF THE CYLINDER END EDGES IN THE SEMICIRCULAR FLOAT SECTIONRECESSES, THE FLOAT SECTIONS BEING SPACED OUTWARDLY OF THE CYLINDERBETWEEN THE SEMICIRCULAR RECESSES.